An electric element has been developed, the element having the bridge, nano-wire or point-contact etc. placed between the opposing electrodes (patent literature 1 for example). Meanwhile, to establish manufacturing technology for the single electron transistor, the inventors have focused on a gold nanoparticle as Coulomb island in single-electron device, and used STM and clarified that the gold nanoparticle with particle diameter of 1.8 nm functioned as Coulomb island at ambient temperature. In addition, to construct an electronic device on solid substrate, the inventors used electroless plating and established the method for manufacturing nanogap electrodes with a gap separation of 5 nm at a high yield rate at a time. Furthermore, the inventors reported on function of the single electron transistor, in which the gold nanoparticle protected by the alkanethiol molecule was placed between the nanogap electrodes by chemical adsorption (Non-Patent Literatures 1 to 5).